In an electrophotographic color printer capable of forming an image using cyan, magenta and yellow toner agents, it is possible that an image (hereinafter, referred to as a “gray mixed color image”) that is formed by superimposedly printing cyan, magenta and yellow images so as to substantially match a monochromatic image (of an achromatic color such as gray or black) having a predetermined print density is formed on a recording sheet.
As a conventional printer capable of forming a gray mixed color image, a printer is disclosed in Patent Document 1 (Japanese Patent Laid-Open Publication No. 2002-82511).
In the printer disclosed in Patent Document 1, by using a color sample sheet on which a test print of a gray mixed color image and a color sample are printed (the color sample being formed by superimposedly printing images of the respective cyan, magenta and yellow colors, of which print densities are each increased by a predetermined amount, on a black monochromatic image), a color sample closest to the test print is selected. According to a density distribution of the selected color sample, a test print obtained by increasing or decreasing the print density of the gray mixed color image is printed. This process is repeated until the test print matches a minimum distribution density of the color sample.
However, in the printer corresponding to the conventional gray mixed color image, there is a problem that, with respect to the increased or decreased print densities of the cyan, magenta and yellow colors, a user cannot further perform fine adjustment or perform color balance adjustment for intentionally modifying hue to suit preferences of the user.
In view of the above-described problem, an image forming apparatus and a control program are desired that allow image formation density adjustment matching intention of a user to be easily performed.